Each emitter has a 33ohm resistor. The regulator is a standard DE7805 that i use for every project. These dont normally get this hot unless they are shorted out. I even had a DE7812 running 48 high power LEDs (in 15 sets) and it didnt get this hot.
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Each emitter has a 33ohm resistor. The regulator is a standard DE7805 that i use for every project. These dont normally get this hot unless they are shorted out. I even had a DE7812 running 48 high power LEDs (in 15 sets) and it didnt get this hot.
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Ive tried removing everything from this circuit. At the moment the 555 is running from a breadboard through a seperate regulator and pin 3 feeds back into the circuit to the transistor. This seperate regulator is cold. The main regulator stays cold until i connect the IR emitters then it gets really hot. Ive checked the current with a multimeter. With both regulators and the 555 it uses 16.5 (milliamps i assume). When i connect the IR emitters it jumps to 101.2 and keeps increasing to about 102. The regulator gets hot quite quick.
Im a little worried about this heat because i need to connect the PIC chip, an RS485 chip and the audio amp circuit and they all use the same regulator.
It looks like using 2 or maybe 3 regulators for the different parts of the circuit should solve everything. Ive got some heatsinks i can put on too.
I still cant figure out why the 555 causes such problems. At the moment the emitters are running from the same board as the PIC. The 555 and its resistors/capacitors etc are running from a seperate regulator and it all works fine. The emitters are drawing way more current than anything else yet its not those causing it. It doesnt appear to be a short and my picoscope shows a fairly stable voltage. I also checked the picoscope when it wasnt connected to anything and the line looked pretty much identical but at 0V so most of it is just noise that the scope picks up.
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You cannot measure the current accurately without a true RMS meter - the circuit is highly non-linear.
You need to show us the complete schematic.
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Ive made and uploaded a schematic based on my PCB layout.
The pins at the top go to the IR receivers and 1 of the speakers.
The ones at the bottom left go to the IR emitters and the other speaker
Bottom right go to some light outputs
Right top are the main connections for power/data/line in
Right bottom goes to the audio amp circuit
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I'm afraid I don't grasp what the 555 is doing. Do you have a link to the website where you found the 555 circuit?
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Sorry, I just realised that schematic is slightly wrong. The POT should connect to pin 7. Its connected right on the PCB though.
Ive uploaded the corrected schematic. I found the website i thought i got it from but it seems i didnt use that one (i dont think i got it to work). The circuit i used is one of the example circuits in PCB Wizard. Ive uploaded a screenshot of that too.
In my circuit ive used a 15K resistor and a 5K POT in series instead of the 100K VR in the example and ive used a 1nF cap instead of 100uF
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No Resistor from the 555 to the Base of the Transistor? How hard do you want to turn that poor Transistor on? If you disconnect pin 3 on the 555 and still have your 7805 (they DO need a heatsink) overheating, then you've damaged your 555.
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